The enthusiastic approval of Adolf Hitler is scarcely the kind of endorsement most authors would want, and the writings of the Prussian military theorist Carl von Clausewitz (1780–1831) certainly had that. His On War was on the list of the top one hundred wholesome titles booksellers in Nazi Germany were supposed to carry. Hailing Clausewitz as the prophet of Absolute War, the Nazi warlord would pore over him at night in the study of the Berghof in the Bavarian Alps with its sign ordering ABSOLUTE SILENCE. He would quote him endlessly at his generals, and, when things started to come apart, Hitler used Clausewitz “as a sort of spiritual talisman,” in the words of the historian Peter Baldwin. Finally, in his political testament, Hitler urged his...